Update README.md

README.md

@@ -13,7 +13,7 @@ If you are a windows user and require macOS to learn XCode, then you can transfo
 <img align="right" src="images/mojave.jpg" height="280"></img>
 - Here I will explain the process of making a bootable USB drive. So be patience:
   - Size of the USB drive can be 8GB or more.
-  - Install any macOS operating system into a VirtualBox.
+  - Install any macOS operating system(macOS Sierra or later) into a VirtualBox.
   - You can download the macOS_Mojave.dmg file from [geekrar.com](https://www.geekrar.com/download-macos-mojave-dmg-file-direct-links/), then open it through VirtualBox and copy "macOS Mojave Installer" into the "Applications" section of macOS.
   - Use USB 2.0 pen drive, to avoid error like: 🚫  sign with [dark background](https://github.com/md-siam/Hackintosh_EliteBook_Folio_9470m/blob/master/images/USB_Disconnected.jpg)
   - Turn on "Terminal" and copy & paste the command below: